对多对多关联EclipseLink的软删除

Question

I want to rewrite the call delete operation (on association table) on a many-to-many association sending by EclipseLink when we use only java code. Let me explain the goal.

I have 3 tables, person, unit and an associative one : PerInUnit, so a person can be in multiple units and a units can contains many people. But I have some dependances on the PeInUnit table (If the person was present or not on a specific date, another table (Participations)), so I can't (and I don't want) delete a record. For that, I make softs deletes, so I can keep records to make some statistics.

I read already about the Customizer and AdditionalCriteria and I setted them to the PerInUnit class. It works perfectly => when I make an em.remove(myPerInUnit); the sql query sent to the db is Update PER_IN_UNIT SET STATUS='delete' WHERE id = #id; and the specified row as "delete" for status. Also, when I read all records, I don't have them with status "delete". But I use explicitly the PeeInUnit class.

Here is the code :

@Entity
@Table(name = "PER_IN_UNIT")
@AdditionalCriteria("this.status is null")
@Customizer(PIUCustomizer.class)
public class PerInUnit implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "GEN_SEQ_PIU")
    @SequenceGenerator(name = "GEN_SEQ_PIU", sequenceName = "SEQ_PIU", initialValue = 1, allocationSize = 1)
    @Column(name = "ID")
    private Long id;
    @ManyToOne(cascade=javax.persistence.CascadeType.PERSIST)
    @JoinColumn(name = "PER_ID")
    private Person person;
    @ManyToOne(cascade=javax.persistence.CascadeType.PERSIST)
    @JoinColumn(name = "UNI_ID")
    private Unit unit;
    @Column(name = "STATUS")
    private String status;
    //Constructor, getters, setters
}

And the code for the PIUCustomizer :

public class PIUCustomizer implements DescriptorCustomizer {

    @Override
    public void customize(ClassDescriptor descriptor) {
    descriptor.getQueryManager().setDeleteSQLString("UPDATE PER_IN_UNIT SET STATUS = 'delete' WHERE ID = #ID");
    }
}

Here come the problem : As I use EclipseLink with bidirectionnal relationship I want to make some instruction like myUnit.getPeople.remove(currentPerson); (remove the current person from the unit "myUnit"). But EclipseLink sent the following instruction (during commit !) :

DELETE FROM PER_IN_UNIT WHERE ((UNI_ID = ?) AND (PER_ID = ?))

instead of the

Update PER_IN_UNIT SET STATUS='delete' WHERE ((UNI_ID = ?) AND (PER_ID = ?))

that I expected and raise (obviously, because of dependances (FKs)) the following exception :

Query: DataModifyQuery(sql="DELETE FROM PER_IN_UNIT WHERE ((UNI_ID = ?) AND (PER_ID = ?))")
    at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:157)
    at test.Crud.update(Crud.java:116)
    at test.Test.runTest(Test.java:96)
    at test.Test.main(Test.java:106)
Caused by: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLIntegrityConstraintViolationException: ORA-02292: integrity constraint (PEOPLE.FK_PAR_PIU) violated - child record found

Other problem (in the same kind), when I make something like System.out.prinln(myUnit.getPeople()) I have all the people in the unit "myUnit", including them having status 'delete'.

Is it possible to change some code/instructions/Customizer/etc in eclipseLink to change the delete call from person for PerInunit table, or I have to make my own queries and use them instead of using powerful of orm ?

Thanks for your answers and please forgive me for my poor english !

Fab

Answer 1

You should not be getting a delete when you call myUnit.getPeople.remove(currentPerson) unless you mapped Unit to Person with a ManyToMany using the PER_IN_UNIT table. Since you have an entity for the PER_IN_UNIT table, this would be wrong, as it really should be a Unit-> PerInUnit OneToMany mapping and then a PerInUnit -> Person ManyToOne mapping. The myUnit.getPeople.remove(currentPerson) call would then simply be getting the PerInUnit instance and marking its status as deleted, or dereferencing it and letting JPA call remove, thereby using your soft delete SQL query.

By using a ManyToMany mapping for the PER_IN_UNIT table, this mapping is completely independent to your PerInUnit entity mapping, and knows nothing about the entities that maybe cached or the soft deletes required to remove them. If you don't want to map the PER_IN_UNIT table as an entity, see http://www.eclipse.org/forums/index.php/t/243467/ which shows how to configure a ManyToMany mapping for soft deletes.